#include "Kernel.h"

#include <iostream>

using std::next;

Kernel::Kernel(const unsigned int RunQ_max_length, const List<PhysicalPage> &free_pages, const List<PhysicalPage> &busy_pages)
: free_pages(free_pages), busy_pages(busy_pages), swapped_page(nullptr) {
    RunQ.reserve(RunQ_max_length);
}

void Kernel::page_fault(std::vector<PTE> *page_table, const unsigned int idx) {
    std::cout << std::format("[kernel:page_fault] Handling {} started", idx) << std::endl;

    PhysicalPage *page;
    if (!this->free_pages.is_empty()) {
        page = free_pages.get_head()->prev;
        free_pages.remove(page);
        busy_pages.insert_tail(page);

        std::cout << std::format("[kernel:page_fault:free] Found free page #{}, using it", page->PPN) << std::endl;
    } else {
        std::cout << "[kernel:page_fault] No free pages available, trying to swap..." << std::endl;
        for (PhysicalPage *curr = busy_pages.get_head();; curr = curr->next) {
            if ((*curr->PT)[curr->idx].R)
                (*curr->PT)[curr->idx].R = false;
            else {
                std::cout << std::format("[kernel:page_fault:random] Selected physical page #{} for replacement", curr->PPN) << std::endl;

                curr->PT->erase(next(curr->PT->begin(), curr->idx));
                page = curr;
                busy_pages.set_head(curr->next);

                std::cout << std::format("[kernel:page_fault:random] Auto-advanced the list of busy pages to ppn {}", busy_pages.get_head()->PPN) << std::endl;
                break;
            }
        }
    }

    page->take_up(page_table, idx);
    (*page_table)[idx].PPN = page->PPN;
    (*page_table)[idx].P = true;
    (*page_table)[idx].R = false;
    (*page_table)[idx].M = false;
}

void Kernel::stat_update() {
    int i;
    PhysicalPage *curr;
    for (i = 0, curr = busy_pages.get_head(); curr && i < 10; ++i, curr = curr->next) {
        if ((*curr->PT)[curr->idx].R) {
            (*curr->PT)[curr->idx].R = false;

            std::cout << std::format("[kernel:update_job] Updating ppn {} status", curr->PPN) << std::endl;
        }
    }
}